Dangerous Points Research Articles

镁合金车轮动态特性分析及弯曲疲劳寿命预测

本文尝试应用有限元分析软件ANSYS workbench，对镁合金车轮进行弯曲疲劳仿真分析，找到该车轮上应力最大的点即危险点和该点上相对应的应力值，利用所得应力值与名义应力法对车轮的寿命进行预测，并将得到的结果与通过软件分析所得结果进行比较；对车轮的其他动态特性进行分析，再将分析结果与铝制车轮进行对比，研究结果提出了车轮合理设计的发展方向。 In this paper, bending fatigue simulation analysis was carried out on the magnesium alloy wheels using the software ANSYS workbench of finite element analysis. For the wheels studied, the stress of dangerous points and the corresponding stress values were obtained. Moreover, the fatigue life of the wheel has been predicted based on the nominal stress method, and the results predicted were compared with the results through the analysis of the software. Other dynamic characteristics of wheels were also analyzed, and then compared with the analysis results of aluminum wheels. The results indicate a design development direction for wheels.

Finding and characterizing hidden dips in roads

Sometimes when connecting a crest vertical curve, followed by a sag and another crest, a road disappears from the view of a driver to reappear later. Then, there is a loss of path or a hidden dip in a road. It is essential to avoid losses when they hide dangerous points, such as intersections or unexpected changes in direction. In addition, this loss disrupts drivers and its effect depends on quantitative relationships between the variables involved in the problem. This paper presents a quantitative procedure for studying hidden dips in roads. The method is based on calculating the sections visible and hidden by a driver using a Geographic Information System. An application to a Spanish road is presented. Procedure results were compared with in situ carried out studies and with a video of the highway recorded using a Global Positioning System equipped video camera embarked in a vehicle. The main quantitative issues related to hidden dips are discussed.

The role of orature in African socio-cultural space

The spoken words are more natural and perhaps better understood than the written letters, which are invented to capture and to re-enact human mind, intention, emotion, opinion, view, experience and prediction among other things. Oral narratives, all over the world, set the pace for the written literature. It is an integral part of every human culture. However, the sophistication of the modern world, particularly the globalisation, has directly or indirectly affected the potency of oral narratives in Africa. Having discovered the neglect of orature in Africa as a whole and in the Yoruba land in particular, this article seeks to explain the essentials of this aspect of life which is at a dangerous point of extinction. The study sets its search light on certain elements of African oral literature such as folklores, myths, legends, proverbs and oral poetry which emanate from the Yoruba community. Using the theme study method/approach, the article aims at reversing the dying fortune of the oral narratives being a tool to achieving sustainable socio-cultural transformation among the African people. Key words: Orature, folklores, myths, legends, proverbs, socio-cultural space, sustainable development.

Finite Element Analysis for Turbine Blades with Contact Problems

AbstractTurbine blades are one of the key components in a typical turbofan engine, which plays an important role in flight safety. In this paper, we establish a establishes a three-dimensional finite element model of the turbine blades, then analyses the strength of the blade in complicated conditions under the joint function of temperature load, centrifugal load, and aerodynamic load. Furthermore, contact analysis of blade tenon and dovetail slot is also carried out to study the stress based on the contact elements. Finally, the Von Mises stress-strain distributions are obtained to acquire the several dangerous points and maximum Von Mises stress, which provide the basis for life prediction of turbine blade.

Application of multi-stage multi-objective multi-disciplinary agent model based on dynamic substructural method in Mistuned Blisk

A method called multi-stage multi-objective multi-disciplinary agent model based on dynamic substructural method (MSMOMDAM-DSM) is proposed. For a large amount of calculation, it can increase the mistuned blisk's computational efficiency more significantly comparing with the traditional probability analysis method when the request of computational accuracy is satisfied. Deterministic analysis is investigated based on the improved hybrid interface substructural component modal synthesis method (IHISCMSM). It demonstrates that the symmetry is broken and the localization phenomenon is observed when the blisk is mistuned. Meanwhile, the frequency response function (FRF) manifests that multiple peaks are observed in different frequencies when the mistuning level is greater than 0% which are caused by the combined behavior of resonance and mistuning. On the base of deterministic analysis, the most dangerous point of mistuned blisk is extracted as response amplitude and the probability analysis is investigated. The probability density distribution function (PDDF) of random variable is given and the limit state equation (LSE) of radial deformation, sampling history, simulation sample, cumulative distribution function (CDF) and histogram distribution are obtained. The sensitivity and the scatter diagram are also analyzed which manifests that some variables are positive while some are negative and the rotational speed is the importance degree. Probability design and inverse probability design are also researched which lay a solid foundation for designing safe and reasonable blisk. At last, it is verified that the computational accuracy and efficiency of MSMOMDAM-DSM is superior to support vector machine-response surface method (SVM-RSM).

Contact Stress Analysis and Fatigue Life Prediction of a Turbine Fan Disc

AbstractFan discs are critical components of an aero engine. In this paper, contact stress and life prediction of a turbine fan disc were investigated. A simplified pin/disc model was conducted to simulate the practical working condition under applied loads using finite element (FE) analysis. This study is devoted to examining the effects of interface condition of pin/disc such as gap and coefficient upon the maximum stress. The FE model indicated that the maximum stress occurs at the top right corner in the second pin hole, and larger gap or friction coefficient has a significant effect on the maximum stress. In addition, FE analysis without considering friction is also conducted. The results show that the dangerous point is similar to the result which considers friction and the stress state is relatively larger than that of considering friction. Finally, based on FE analysis result, life prediction for the fan disc is conducted to combine the material

Fluid-Structure Interaction Study on the Influence of Circular Gap of Parachute on Inflation Performance with Fixed Payload

In order to study the influence of circular gap controlled by the tearing force on rescue parachute inflation performance, the Arbitrary Lagrange-Euler (ALE) coupling method is utilized to simulate the inflation process of the circular gap rescue parachute with fixed payload; the contact failure model of the open of circular gap was built by the sewing force of the sewing thread. The canopy structure model influenced by fabric permeability performance is proposed, and the differential pressure of permeable fabric is described in Ergun equation through the textile material permeability test. The numerical results calculated by LS-DYNA are compared with the results of airdrop test and the empirical method of parachute-payloads dynamics, and it is shown that the steady drag coefficient and transient shape during inflation are more consistent with the airdrop test results, and the dimensionless initial inflation time and the maximum equivalent opening shock are more realistic. The stress variations of each gore unity during inflation are investigated. The most dangerous time-space state point during inflation process was discovered. With the study of the influence of the circular gap structure of parachute on inflation performance, the numerical results show the circular gap structure can reduce the opening load and adjust the time of two inflation stages, which reduces the maximum effective stress in dangerous parts and improves the safety of canopy.

Fatigue Life Prediction of the Rocket Engine’s Pipeline under Random Loads

Based on the random vibration theory and numerical analysis method, the paper presents a process of carrying out the fatigue life prediction for pipeline of a rocket engine under random excitation. The numerical analysis adopt the power spectrum density of acceleration as random loads. The material parameters of the simulation contains two straight lines in double logarithmic coordinate. The location of danger points is found and the root mean square stress, fatigue life of it is acquired in different excitation directions. The results show that the root of the ball head is the location of danger points, whose fatigue life is 3763 seconds. Furthermore, the location of danger points and its fatigue life obtained from numerical analysis are consistent with the test.

Real-time EEG-based detection of fatigue driving danger for accident prediction.

This paper proposes a real-time electroencephalogram (EEG)-based detection method of the potential danger during fatigue driving. To determine driver fatigue in real time, wavelet entropy with a sliding window and pulse coupled neural network (PCNN) were used to process the EEG signals in the visual area (the main information input route). To detect the fatigue danger, the neural mechanism of driver fatigue was analyzed. The functional brain networks were employed to track the fatigue impact on processing capacity of brain. The results show the overall functional connectivity of the subjects is weakened after long time driving tasks. The regularity is summarized as the fatigue convergence phenomenon. Based on the fatigue convergence phenomenon, we combined both the input and global synchronizations of brain together to calculate the residual amount of the information processing capacity of brain to obtain the dangerous points in real time. Finally, the danger detection system of the driver fatigue based on the neural mechanism was validated using accident EEG. The time distributions of the output danger points of the system have a good agreement with those of the real accident points.

Quality evaluation of spray-dried powder prepared from aonla juice blended with pigment-rich vegetable juice during storage

Aonla is a rich source of natural ascorbic acid and polyphenols, while vegetables are rich source of pigments. The aim of the present study was to provide better nutritional quality of spray-dried aonla powder by enriching it with carotenes and anthocyanins. Spray-dried powder was prepared either from pure aonla juice or by blending it with 10 per cent carrot or/and beet juice using a laboratory model spray dryer. Powder samples were stored in food grade laminated aluminium foil pouches up to 6 months under ambient conditions. Ascorbic acid (3700 mg/100 g) and polyphenols (19.74%) were found highest in pure aonla powder. Blended powder of aonla and beet showed a significant increase in anthocyanins content from 0.47 to 14.25 mg/100 g, while that of aonla and carrot showed an increase in total carotenoids from 0.53 to 6.92 mg/100 g. The contents of ascorbic acid, total carotenoids and anthocyanins in powder prepared from blended juice of aonla, carrot and beet were observed to be 3478, 6.69 and 12.97 mg/100 g, respectively. During storage, an increase in anthocyanins and non-enzymatic browning were noticed in all spray-dried powder samples whereas, the contents of ascorbic acid and total carotenoids decreased. The amount of ascorbic acid was found highest (2442 mg/100 g) in pure aonla powder followed by powder obtained from mixed aonla and carrot juice (2193 mg/100 g) after 6 months of storage. The content of polyphenols did not change significantly during storage in any of the powder samples. The critical and danger points in terms of equilibrium moisture content (EMC) for spray-dried aonla powder were observed to be 1.96 and 1.86 per cent, respectively. At 50% relative humidity (RH) colour of the powder changed from white to brown and lump formation started. The liquefaction of powder started and mould growth appeared at 80% RH. Carotene and anthocyanins enriched spray-dried aonla powder could be prepared and stored in hermetically sealed packaging up to 6 months under ambient conditions without much deterioration in nutritional quality.

Discrete element method for emergency flow of pedestrian in S-type corridor.

Pedestrian flow in curved corridor should be modeled before design because this type of corridor can be most dangerous part during emergency evacuation. In this study, this flow is analyzed by Discrete Element Method with psychological effects. As the turning slope of corridor increases, the evacuation time is linearly increases. However, in the view of crashed death accident, the case with 90 degree turning slope can be dangerous because there are 3 dangerous points. To solve this matter, the pedestrian gathering together in curved part should be dispersed.

Study on Stability of Layered Roof Surrounding Rock Reinforced by Anchor in Rectangular Roadway

Under the assumptions of plane strain, vertical normal stress and shear stress distribution in surrounding rock of rectangular tunnels before and after installing anchor cable are studied. And according to the mechanics of materials, the formula of stress distribution in the roof is corrected. According to the corrected formula of the stress distribution, the dangerous points are found. And the dangerous point location does not change before and after installing anchor cable. It still locates in the middle and ends of roadway roof. Just the dangerous stress value decreases after installing anchor cable. There are the maximum tensile stress in the midpoint roof and the maximum shear stress on both ends of the roof.

Study on the Maintenance and Management of VRLA Battery

The paper introduced the basic characteristics, maintenance requirements and backward cell processing method of Valve Regulated Lead Acid Battery (VRLA) based on the practice of substation communication, elaborated the charge-discharge test battery requirements. This paper discussed the test of battery operation and maintenance, charge and discharge risk. Through the test methods of battery communication charging and discharging and the steps of analysis, we find out the possible dangerous points in processing of charging and discharging, and at the same time, we list the typical examples on safety risk and carry on the analysis on accident cause to put forward the pre-control measures.

Reducing seclusion and restraint during child and adolescent inpatient treatment: still an underdeveloped area of research.

Half of all youth hospitalized in inpatient psychiatric facilities manifest aggressive behavior. When aggression escalates to the point of danger, measures must be employed to guarantee safety of both patients and staff. In this paper, the current empirical evidence for intervention models to reduce restriction and restraint utilization in children and adolescents is reviewed. PubMed and PsycINFO were searched for English-language articles published between 2006 and 2013. Included were empirical studies of child or adolescent inpatient populations using a pretest and posttest design. Included in this review are three empirical papers describing two different intervention models that met the inclusion criteria. The review indicates there are two empirical supported intervention models that are helpful in reducing seclusion and restraint utilization in children and adolescents. The promising empirical findings support evidence and application to the child/adolescent population for at least three of the six National Association of State Mental Health Program Directors core strategies for restraint reduction. The modest number of empirical papers reflects that reducing restrictive measures in child/adolescent inpatient treatment remains an underdeveloped area of research.

The Present Situation of Rural Housing and the Seismic Performance Analysis

In recent years, the security of rural building has attracted more and more attention. The analysis of the existing problems of rural building summarized the distribution of dangerous points, and the use of finite element analysis method was carried out on the typical farmhouse seismic time history analysis to find out seismic weak places in the masonry structure buildings. Then the study also shows that the system with ring beam and structural concrete column has good reinforcement effect. This study plays an important role in improving the rural housing construction measures and the seismic performance of the building.

The Simulation and Improvement of the Heating Furnace Lifting Framework Based on ANSYS

Step-type heating furnace is a kind of mechanized furnace hearth furnaces, due to the corrosion of heating furnace lifting framework is serious, which needs to repair. This article uses the Pro/E to build heating furnace lifting framework model, and then it is leaded to ANSYS which can analysis the stress of framework. Firstly, the framework model that has been corroded and damaged should be analyzed for summing up the framework’s damage and dangerous points and determining the framework reparative plan. Then framework model after being repaired needs to analyze with the same load, the analytical result of which should be compared with that of original design’s framework, and reparative plan should be corrected and examined. Finally, the reasonable framework reparative plan will be determined.

Electric Power Dispatching Operation Danger Point Analysis and Control Research

the safety of power grid scheduling is the key to ensure the safe and stable operation of power grid. Scheduling work dangerous point analysis, formulate measures, strengthen precontrol is important means to ensure the safety of power grid. Introduces the analysis of the dispatching work dangerous points and preview. This paper expounds the main work and status quo of power system dispatching operation management, and puts forward solutions.

Deformation Prediction of the Bipolar Plate Stamping

Bipolar plate is the key component of proton exchange membrane (PEM) fuel cell and represents a significant part of the overall cost and the total weight in a fuel cell stack. Many research have been done on the manufacturing methods of bipolar plate, among which stamping is very popular. With the increasing of the channel number and complexity, its dimensional error caused by sprinkback will change a lot, even under the same forming process. And the risk of crack is also different. These all impact the quality of bipolar plate. In order to predict deformation of channels and the plate’s quality, the displacement along X-axis, the strain and stress state, and the displacement along Z-axis are measured. The results show that 1) the risk of crack increases with the increasing of channel number; 2) the springbacks increase with the increasing of channel number; 3) the most dangerous point locates on the right internal fillet of the plate’s last section.

Estimating thermal boundary conditions of boiler membrane water-wall using decentralized fuzzy inference with sensitivity weighting

The thermal boundary conditions including the fireside heat flux, temperature of water–steam mixture in water-wall tubes and heat transfer coefficient on the inner surface of membrane water-wall, are estimated at the same time using the decentralized fuzzy inference (DFI) method with the sensitivity weighting based on the local measured temperature on the back of membrane water-wall. The influences of different initial guessed thermal boundary conditions, the measurement points, and the temperature measurement errors on the estimated results are discussed, and comparisons with the conjugate gradient method (CGM) are conducted. The study shows that the thermal boundary conditions of membrane water wall, the temperature distribution on the fireside and the positions of the dangerous points can be determined more accurately by the proposed method. It is concluded that DFI method with the sensitivity weighting is of better anti ill-posed characteristic. It would provide necessary basis for analyzing and monitoring the operation state of power plant boilers.

Vibration Fatigue Analysis for the Frame of Vehicle Equipment

Traditional fatigue analysis approaches could not solve the structure fatigue failure caused by resonances. The time domain simulation approach which took the structural intrinsic property into account was presented to solve vibration fatigue problems. The vibration fatigue failure of the frame of vehicle equipment was studied. Broadband vibration loads were put into the finite element model of the frame as excitations, the stress power spectral density of a dangerous point was calculated. At last, the Dirlik method and the time domain simulation approach were used to calculate the fatigue life. The results show that the damage caused by the first-order vertical flexural vibration is the largest; the result of the time domain simulation approach has a good agreement with the experimental result when compared with the frequency domain method.